Research for a good x86 disassembly program. What codeye did was to force an early RET (0xC3) at the beginning of the SetBacklight routine, which starts with a PUSH (0x55) instruction.

While this solution does work, it is less than perfect. A better solution would be to find out how to make the laptop change brightness based on the keycodes it receives. Even better would be to write a new Asus ACPI driver. I have some ideas on that, more on that later.